Heating Element Terminal Radial Displacement Pivot
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Solution Overview
Problem
Existing mechanical support terminals for heating elements in MOCVD reactors face issues with thermally induced stress due to high temperature differences, leading to mechanical stress and the risk of short circuits, as they allow expansion in multiple directions, compromising the strength and creep resistance of refractory metals.
Innovation Solution
A terminal with a support device that allows displacement primarily in the radial direction, decoupling it from tangential and axial directions, using a single main spring direction to manage thermally induced deformation, thereby reducing stress and preventing bending moments within the heating element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fixed terminals are used to support the heating element, then the heating element is kept in a predefined position, but thermally induced stress is generated inside the heating element material during heating up to 2200° C.
Solution Approach 1:
The terminal structure is transformed from a fixed rigid connection to a dynamic system with a pivot point that allows rotational movement. This enables the heating element to accommodate thermal expansion and deformation dynamically during heating cycles, reducing thermally induced stress while maintaining positional stability through controlled movement about the pivot axis.
2Stress or pressure
If flexible elements are used to allow expansion in preferable directions, then thermal stress is reduced, but mechanical loads within heater elements increase with displacement, producing stresses comparable with reduced strength of the heating elements above 1200 to 1400° C.
Solution Approach 1:
The terminal structure is segmented into distinct functional components: a fixed mounting portion, a pivot point, and a support arm. This segmentation allows the system to provide flexibility where needed (at the pivot) while maintaining rigidity in other portions, thereby reducing thermal stress without creating excessive mechanical loads that would compromise the heating element's strength at high temperatures.
3Stress or pressure
If U-form springs are used to compensate thermally induced stress, then movement of the connection position is allowed, but the heating element can extend in two or more directions leading to risk of contact with other parts and short circuits
Solution Approach 1:
The terminal structure employs asymmetric geometry with a designated pivot point that constrains movement to a specific rotational axis. This asymmetric design allows thermal compensation in the direction of rotation while preventing extension in other directions, thereby maintaining electrical isolation and preventing short circuits while still accommodating thermal deformation.
4Stress or pressure
If terminals allow freedom of movement in two or more directions of deformation, then thermally induced stress is reduced, but at least one bending moment is created inside the material of the heating element
Solution Approach 1:
The terminal structure transforms the support system from a multi-degree-of-freedom flexible connection to a controlled single-degree-of-freedom rotational joint. This dynamic constraint allows thermal expansion to be accommodated through rotation about the pivot point while minimizing bending moments in the heating element by aligning the pivot axis with the primary direction of thermal deformation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces thermally induced stress, allows for the use of cheaper materials, and increases the lifespan of the heating element by limiting movement to less than 10% in undesirable directions, while maintaining mechanical stability in other directions.
Implementation Method 1
the heating element tries to extent its dimensions and therefore thermally induced stress is generated inside the material of the heating element
Implementation Method 2
Said known terminals comprise different kinds of U-form springs, which are able to allow a movement of the connection position between the heating element and the terminal
Data Source
AI summary
A terminal for mechanical support of a heating element, includes a base device, a mounting device, the mounting device adapted to support the heating element, and a support device connecting the base device to the mounting device, the support device allowing displacement of the heating element about a radial axis and less than about 10% displacement of the heating element about a tangential and/or axial axis.